BEFORE: Check your hotend fan is spinning above 50C. Also, ensure your filament is DRY.
1 Check your extruder can extrude back and forth without the base of the toolhead attached and no clicking.
2 Check there is no piece of filament obstructing anything in the small narrow filament path under the extruder itself but inside the SB.
3 Check the bowden piece inside the toolhead has no filament inside or on top/bottom.
4 Check that the base of the small bowden piece (11mm typically in size once fully inserted as measured from the top of the base part of the toolhead) once removed at the top of the hotend has no filament obstructing it.
If it does, then consider heating up the hotend and pushing a noclogger or declogging tool UP with the nozzle off to clean out any rubbish.
5 Quick and dirty: Lift the latch on the SB/move the left piece out (part of the double latch) and heat up the hotend, then jam a noclogger/declogging tool down the whole toolhead until it reaches the nozzle.
Jam it in and out multiple times until it moves cleanly and clearly hits the base metal of the nozzle; it's worth measuring the amount of metal that passes through to check it reaches all the way down to the nozzle visually once you've taken it out as a general rule of thumb.
6 Adjust the adjustment screw to tighten up such that it just blocks the filament from going through the extruder, then back it off by 1/4 of a turn but still retaining the blocking nature of the filament going in; it should grab easily and pull/push when you extrude/retract.
Note that I have never experienced a nozzle clog in 6+ years of printing; it's extremely unlikely to be a nozzle clog.
Tools you can use to declog
Note that this has a better non 3D printed handle than the noclogger below; it's the ONLY Creality product I'll recommend.
Clog Poke Creality (UK): https://www.amazon.co.uk/Creality-Cleaning-Piercing-Printing-Disassembly/dp/B0D3HKY3M2
Clog Poke Creality (US): https://www.amazon.com/Creality-Cleaning-Piercing-Disassembly-Thoroughly/dp/B0D3FD43W7
Noclogger (US): https://noclogger.com/
A suitably sized allen key (not as easy as a decent declogging tool but it works in a pinch).